Fig. 25
From: Paediatric brainstem: A comprehensive review of pathologies on MR imaging
A 9-year-old child with headache and vomiting: a Sagittal T1-weighted image shows expansion of the pons with hypointense signal (asterisk). b Axial T2-weighted image shows increased signal intensity involving the pons (asterisk) with the basilar artery (arrow) appearing engulfed by the lesion. Posteriorly the fourth ventricle is compressed (dotted arrow) (flat fourth ventricle sign). c No significant contrast enhancement is noted within the lesion